a. The Field of the Invention
This invention relates to an apparatus for washing fabrics and more particularly to an apparatus for continuously, uniformly and thoroughly washing continuous pieces of fabrics, particularly knitted fabrics and the like, which are lengthwise admitted into a plurality of washing tanks while being maintained transversally spread for its full width. The apparatus washes the fabric by maintaining it in a completely immersed and tensionless or "relaxed" condition in a washing liquid bath.
B. The prior Art
This art is a known and well worked one. An apparatus which has been proven to provide satisfactory washing and treatment of continuous pieces of fabric has been described in the U.S. Pat. No. 3,646,785, corresponding to the British Pat. Specification No. 1,317,938. This prior art apparatus is provided with a plurality of washing tanks in which the continuous fabric is sequentially guided by progressed by means of pluralities of rollers including washing rollers and fabric widening rollers. The washing rollers are hollow and apertured for issuing washing liquid through their outer surfaces for full impregnation with the fabric. The widening rollers each have a helically ribbed surface so arranged that opposite sideward pulls are applied to the fabric when rotated adjacently thereto.
As set forth in the above-mentioned patent disclosures, the characteristic texture of a knitted fabric, such as those widely mass-produced by circular knitting machines and widely made use of, for example, for ladies' garments, is such that it is not adapted to resist tensions. It is subject to elongation in any direction in which a pull is exerted thereon. Additionally, such knitted fabrics are subject to curl or roll-up, particularly when wet, from the edges towards the center portion of the piece of fabric. On the other hand, such fabrics can be, and generally are, ornamented by printing processes and require a very careful final treatment, principally a so-called "finishing" treatment including a plurality of preliminary and of forced final immersion washing steps. The combined action of the washing and widening rollers of the prior art apparatus described above which are positioned beneath the level of the liquid baths that are maintained and recycled into washing tanks, has been proven capable of ensuring a generally satisfactory treatment for the fabtric, especially when the same was maintained well open and fully spread and slightly tensioned in the longitudinal and/or transversal directions.
It has, however, been found that a more satisfactory washing will occur if the washing treatment includes at least one step in which the fabric is maintained immersed in a completely tensionless condition, the condition being generally termed in the art as a "relaxed condition". Such a relaxed condition has heretofore been believed to be unfeasible in the operation of a continuously-run apparatus which has roller means that are designed for continuously pulling the fabric along and through the apparatus.
Further, it has been found that after a length of fabric, in particular a knitted fabric, is immersed into and progressed along a liquid path in a tensionless condition that the proper alignment of the fabric along the predetermined path lying in the longitudinal vertical plane of symmetry of the apparatus will be seriously affected by unpredictable and uncontrollable sideward displacements of relaxed portions of the length of the fabric.
It is, therefore, a principal object of this invention to provide a new and improved apparatus for the final immersion washing of continuous lengths of fabrics, including certain new and advantageous means and devices, and combinations and arrangements of said means and devices, as set forth hereinbelow, by which a proper and efficient washing treatment can be performed in the apparatus, the treatment including the washing of the fabric in relaxed condition and the re-alignment of the fabric in its proper path, if and when a misalignment occurs.